Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 230123

Area Forecast Discussion
National Weather Service Gaylord MI
923 PM EDT Thu Jun 22 2017

Issued at 922 PM EDT Thu Jun 22 2017

Deep convection is ramping up substantially along/s of the US-10
corridor downstate. There is still some activity upstream in WI
that will bring rain (higher amounts south of M-32), but the
strongest storms will clearly be downstate. Think it will be very
difficult to realize a svr threat here.

Activity presently w/nw of MKG is moving ene-ward, and could
still bring some healthy rainfall amounts in se portions of the
forecast area. Elsewhere, heavy/excessive rain is also unlikely.

Drying trend from the nw will take some time to make robust
inroads. Current forecast is slow to end pops overnight, with
more drastic drying Fri morning. This still looks good.


.NEAR TERM...(Tonight through Friday)
Issued at 316 PM EDT Thu Jun 22 2017

High impact weather potential: Showers and thunderstorms with
potential heavy rainfall. A few storms may be severe with damaging
winds and large hail the threats. Need to monitor rivers for
potentially higher rises if total QPF through the night happens to
near a couple inches.

Pattern synopsis and forecast:

Fast westerly flow aloft continues over the area with the next in a
series of shortwaves pressing through Wisconsin, spreading an axis
of deeper moisture (PWATS now in the 1.75" to 2.00" range) through
the western Great Lakes. This out ahead of a cold front that
stretched from central Lake Superior through NW Wisconsin. Low to
mid level WAA and additional upper divergence was helping to expand
showers and a few thunderstorms ahead of the front. Not much else
has developed from anything diurnally driven despite nrn lower
BLCAPES 1000-1500j/kg (less in eastern upper), as there is a lack of
a focusing mechanism, aided by the fact there was some subsidence
warming aloft from behind this mornings rainfall. Low clouds have
held tough most of the day from roughly M-32 north, keeping heating
at a minimum, with the warmer readings south of there, reaching the
upper 70s to lower 80s.

Heading through the late afternoon and evening hours, am expecting
showers to expand further as the aforementioned forcing moves in
over the region, and while the LLJ will try to strengthen, back some
ahead of the shortwave, and result in increasing low level
convergence. MUCAPES do not appear to wanna eclipse more than 1200
j/kg across the srn CWA, with much less instability further north,
especially into eastern upper. Still looking at a marginal risk for
a severe storm or two M-32 south, with slight risk scraping portions
of M-55 corridor. Damaging winds to 60 mph and large hail to 1 inch
still the threats. Heavy rainfall appears to be the main player here
with such a moist air mass. Expect periods of very heavy rain,
focused more so in the evening to maybe a few hours past midnight.
Many areas of nrn lower, still thinking more likely along and south
of a line from the GTV Bay region over to Alpena. Could easily see
over an inch of rain in this area. Will need to keep a close eye on
rainfall totals, RFC max 48hr contingency forecasts are as high as
2". This would have some impacts on area rivers and streams. As of
right now, there are no significant rises anticipated that would go
into flooding. Rainfall starts to trail off late tonight into Friday
morning, especially as the cold front slowly crosses the region. We
will more than likely have to deal with more low clouds and a little
fog until it passes. Cooler and less humid air and and some fairly
decent drying are expected to lead to a great Friday afternoon with
only some high based scattered cumulus. Large scale upper troughing
slides south toward eastern upper tomorrow afternoon with some
colder temperatures aloft combining with secondary sfc troughing,
for the potential of a few showers. This is a low chance/low
confidence setup.

Very mild night SE CWA with mid to upper 60s for lows, while cooler
mid and upper 50s across eastern upper. Highs tomorrow in the 70s.


.SHORT TERM...(Friday night through Sunday)
Issued at 316 PM EDT Thu Jun 22 2017

...Cooler with (mainly) daytime showers/storms...

High Impact Weather Potential...Low risk for not severe
thunderstorms Saturday and Sunday afternoon.

Pattern Synopsis/Forecast...Long wave troughing persists across much
of Canada and into the northern plains/Great Lakes region with long
wave ridging building northward along the west coast...toward the
Gulf of Alaska. Closed/occluding low pressure/short wave energy
moving through the mean trough is sliding through south-central
Canada...with an occluded/cold front arcing into the upper Midwest
then back to secondary low pressure in the central plains. Occluded
low pressure system slides through Ontario/far northern lakes region
through Friday kicking the front through the state. Cooler weather
arrives for the weekend along with the possibility for daytime
instability showers/possibly thunder...with shower activity
augmented by the passage of a secondary short wave late Saturday
night into Sunday.

Primary Forecast Concerns...Minimal. There will be a low end risk
for thunderstorms Saturday afternoon and a little better chance for
thunderstorms Sunday afternoon...with daytime heating and as colder
air aloft slides over the region (core of -22C 500 MB air moves
through Sunday). Best chances will likely be across north-central
and northeast lower Michigan with prevailing westerly flow. But
aside from any brief pulse-severe hailer with low wet-bulb zero
heights...severe weather risk will be minimal. once again through Sunday with high temperatures in
the middle 60s to around 70 both days (coolest on Sunday) and a good
10 to 15 degrees below normal.

.LONG TERM...(Sunday night through Thursday)
Issued at 316 PM EDT Thu Jun 22 2017

The extended forecast, Monday through Thursday, indicates a slow
warming trend across the Great Lakes next week, with a few rounds of
rain showers expected.

At upper levels, a broad upper trough which settled over the Great
Lakes and Hudson Bay during the weekend, will slowly exit east of
the region Wednesday, while an upper ridge strengthens over the
Plains and pushes into the state Thursday. 850mb temps in this
pattern will warm from around 5c to begin the upcoming work week, to
around 12c Thursday in the developing upper ridge. The upper lvl
pattern will help surface temperatures warm from below normal
readings in the upper 60s to around 70 degrees thru Tuesday, before
warming into the mid 70s Thursday.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 737 PM EDT Thu Jun 22 2017

Rounds of showers/storms will migrate southward tonight.
Improving conditions Friday.

Multiple rounds of showers/storms will evolve southward with time
tonight, as a cold front crosses the region. Cigs/vsbys will
lower toward MVFR and in spots IFR conditions. Those conditions
will improve quickly on Friday as drier air moves in.

Westerly winds will persist, becoming a touch gusty at times by
Fri afternoon.


Issued at 316 PM EDT Thu Jun 22 2017

Gradient winds and waves not expected to be of any issue over the
next several days. Generally southerly winds will turn more westerly
overnight into Friday morning behind the passing of a cold front.
Gusty and erratic winds will be possible within periods of showers
and scattered thunderstorms that will be associated with this front,
with the strongest of activity this evening to a few hours past
midnight. There is a small chance for a storm or two to become
severe across the srn nearshore waters, but that chance is fairly
low. Expect some very heavy rainfall however. Skies open up through
the day Friday, with cooler and drier air increasing over the
region. Additional scattered showers and a few potential storms
through the weekend, mainly in the afternoons.




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